Removal of H2S From Coal and
Crude Oil
Christina Fontanos
Bethany Levering
William Pfeiffer
Ryan Smith
What is Hydrogen Sulfide?
• Chemical Formula: H2S
• Colorless gas with rotten egg
odor
• It can be produced by the bacterial breakdown
of organic matter, often in water, as free
oxygen must be absent.
http://www.webelements.com/_media/compounds/H/H2S1-7783064.jpg
Physical Properties
•
•
•
•
•
Molar Mass: 34.8 g/mol
Density: 1.363 g/L
Melting Point: 191 K
Boiling Point: 213 K
Flash Point: 190.8 K
http://wordpress.mrreid.org/wp-content/uploads/2010/09/car-explosion.jpg
• Low boiling point low
density cause H2S to
move into the vapor
phase and stays in the
head space of crude oil
containers.
• The low flash point
illustrates hydrogen
sulfide’s extreme
flammability and
explosiveness.
Why do Chemical Engineers Care?
• Naturally occurring in many crude oils
• Also produced in oil refining processes by the
degradation of the sulfur containing
compounds in crude oil.
• Heavily regulated because
of its high toxicity, so removal
and containment is crucial in
petroleum industry.
http://www.thelostogle.com/wp-content/uploads/2011/10/Oil-Refinery-Pump-Image1.jpg
Hydrogen Sulfide: The Silent Killer
• Highly Toxic
– Concentrations of 700-2000ppm are lethal.
– Cardiovascular and respiratory failure.
• Improper handing and storage conditions can
increase H2S concentrations in containers.
• OSHA Standards
– Concentrations may not exceed 20ppm in general
industry practices
Environmental Concerns:
Treecapitation
• Foul odor
– Rotten eggs
• Greenhouse Gas
• Acid rain
Operational Concerns: Machines Break
While Tripping on Acid
• Flare Gas
– Sulfur Oxides are produced when H2S contaminated
fuels are flared.
• Liquefied Petroleum Gas (LPG)
– Corrosion in copper fuel systems.
– Corrosion in ferrous storage vessels
• Refined Fuels
– Corrosion in copper systems
– Treatment of refined fuels to account for H2S alter the
viscosity of the fuel.
– Gasoline sulfur content limited to 80ppm per gallon
Operational Concerns: Machines Break
While Tripping on Acid
• Crude Oil and Heavy Fuel
– H2S contamination results from thermal cracking of
high molecular weight Sulfur compounds.
– H2S scavenger reside can damage equipment.
• Asphalt
– High storage temperature promotes generation of H2S
by thermal cracking.
– Contains H2S concentrations of up to 10,000ppm
– High vapor:liquid partition coefficient.
• Most H2S concentrates in vapor phase.
– Difficult to treat
Methods for H2S Removal from Crude
Oil: Do Away With the Undesirables
• Crude oil contains 0-3%
sulfur
• Sources of S in crude oil:
thiols, thiophenes,
sulfides, disulfides
• H2S gas must be removed
from crude oil before
transport
http://www.chemistryland.com/CHM107/syllabus/oil%20refinery400.jpg
Methods for H2S Removal from Crude
Oil: Flaring and Sour Gas Collection
• Light hydrocarbons and
impurities captured in
VRUs
• H2S in the headspace of
tanks or wells is
captured and flared off
in emergencies
http://www.tescorp.com/demo_images/Tescorp_Vapor_Recovery_Unit.jpg
• The SO2 product is a
greenhouse gas still
limited by the EPA
http://www.tescorp.com/demo_images/Tescorp_Vapor_Recovery_Unit.jpg
Methods for H2S Removal from Crude
Oil: Hydrodesulfurization (HDS)
• Must be done before
hydrocarbon cracking; S will
poison the cracking catalysts
• High T/high P PBRs with
transition metal sulfide
catalysts on alumina supports
(Co/Mo, RuS2)
• Sulfur compounds are
converted to H2S which are
removed in subsequent units
http://english.sinopec.com/products_service/License/Oil_Refining/im
ages/pic4uhm7n77.jpg
Methods for H2S Removal from Crude
Oil: Gas Stripping
• The oil can be stripped
of H2S using natural
gas
• Oil is passed down
through a contact
tower over trays while
the natural gas flows
up through the column
Methods for H2S Removal from Crude
Oil: Amine Treatment
• Amine Treatment
– Diethanolamine
(DEA)
– Monoethanolamine
(MEA)
– Methyldiethanolamin
e (MDEA)
– Diisopropanolamine
(DIPA)
– Diglycolamine (DGA)
http://b.static.trunity.net/files/185901_186000/185963/amine
-treating.png
𝐑𝐍𝐇𝟐 + 𝐇𝟐 𝐒 ⇄ RN𝐇𝟑+ + 𝐒𝐇+
Removing H2S from Coal
• Major Uses for Coal
– Direct Burning
• Power Plants
– Synthetic Gas
• Gasoline
• Diesel
• Plastics
Removing H2S from Coal
• Direct Burning
– Scrubbers
• Remove SO2
http://www.edillon.com/images/products/industrial/powerPlant.jpg
• Spray steam and cation containing material
– Limestone (Ca2+)
– Magnesium oxide (Mg2+)
– Forms salt
http://upload.wikimedia.org/wikipedia/commons/6/65/SeleniteGypsumUSGOV.jpg
Removing H2S from Coal
• Coal is also converted to synthetic gas (syngas)
– Add Water and Air to Coal
• Syngas - Main Components
– CH4
• H2S
– CO
• H2
– CO2
• H2O
Removing H2S from Coal
• Must remove H2S before using the syngas
• Physical Removal
– Absorb
• Chemical Removal
– Reaction
http://www.statesymbolsusa.org/IMAGES/Utah/CoalAnthracite.jpg
Removing H2S from Coal
• Physical Removal
– Physical Sorbent
• Graphite
• Activated Carbon Fibers
– Physical Solvent
http://img.diytrade.com/cdimg/1259120/14201037/0/1282544617/Activated_Carbon.jpg
• NMP
• Propylene Carbonate
• Chemical Removal
– Chemical Sorbents
• Dolomite
• Limestone
http://upload.wikimedia.org/wikipedia/commons/thumb/c/c3/
Sample_of_propylene_carbonate.jpg/200pxSample_of_propylene_carbonate.jpg
References
• Abbasian, Javad, and Amir Rehmat. "H2S REMOVAL
FROM FUEL GAS DURING COAL
GASIFICATION." Argonne National Laboratory. Web.
• "Sulfur Dioxide Scrubbers." Duke Energy. Web.
• Li, Huixing. "SELECTIVE CATALYTIC OXIDATION OF
HYDROGEN SULFIDE FROM SYNGAS." University of
Pittsburgh. Web.
• Burr, Barry, and Lili Lyddon. "A COMPARISON OF
PHYSICAL SOLVENTS FOR ACID GAS
REMOVAL." Bryan Research & Engineering. Web.